Some observations on the morphology of the newt liver at different stages of inanition

摘要

It was the primary objective of this investigation to observe morphological changes in the hepatic parenchyma or perihepatic subcapsular region which occurred as a result of inanition and to determine when these changes took place. We also wanted to study the effect of starvation on the peripheral blood cells. We were particularly interested in obtaining this information because a relatively large percentage of animals that we obtain from the wild or commercial suppliers do not eat well for 2 weeks or longer after arrival in the laboratory; therefore, we were interested in determining whether food deprivation had any effects on liver morphology and blood cell populations which would prevent us from carrying out studies which were not initiated immediately after the animals had been captured. In order to accomplish these objectives, animals were weighed at various time intervals of starvation and morphometric analyses were performed on light and electron micrographs of hepatic tissue from newts which were starved from 2 to 16 weeks before being sacrificed. Analyses of the results revealed that (1) during the first 2 weeks of starvation of the newt a 17 loss of body weight occurred, but that rate of weight loss diminished as the time of starvation increased, and (2) starvation induced the fragmentation of liver cells thus depleting the lipid, glycogen and mitochondrial content of the liver and creating larger and larger sinusoids as starvation progressed; glycogen granules were quickly and inexorably lost from hepatocyte cytoplasm, but the rate of lipid and mitochondrial loss was much slower. A comparison of the number of mitochondria per unit volume of hepatocyte cytoplasm in control and starved newts suggested that those mitochondria that were present at the 8-week time interval increased in size until the largest were lysed between 8 and 16 weeks of starvation. The substantial changes that occur in the hepatic parenchyma during the first weeks of starvation strongly indicate that newts which are not feeding well in the laboratory should be identified and eliminated from studies involving the liver and its metabolism.